1. Field
Exemplary embodiments of the present invention relate generally to a lenticular unit for realizing three-dimensional auto-stereoscopic display.
2. Discussion of the Background
Three-dimensional (3D) effects of an object may be achieved by binocular disparity when a viewer or an observer views the object through retinas of his or her left and right eyes simultaneously in different directions and then recognizes it by means of the brain. Therefore, to display 3D images, left and right eyes of a viewer are allowed to view different images using the principle of the binocular disparity, enabling the viewer to recognize the 3D images.
3D display technology may be roughly classified into stereoscopic display technology, which requires viewers to wear special glasses such as shutter glasses and polarized glasses, and auto-stereoscopic display technology, which does not require viewers to wear glasses.
An auto-stereoscopic display device may be generally classified into a parallax barrier 3D display device and a lenticular 3D display device. The parallax barrier 3D display device includes a vertical grid-shaped parallax barrier with openings or slits, mounted in front of a display screen or panel having pixels arranged in a matrix of rows and columns. The parallax barrier separates a right image and a left image associated with the right eye and the left eye of a viewer, respectively, causing binocular disparity between different images on the display panel, thereby enabling the viewer to recognize 3D images. Disadvantageously, however, the parallax barrier 3D display device may suffer from diffraction caused by the slits. On the other hand, the lenticular 3D display device uses a lenticular screen or a lenticular lens sheet with a column-wise array of semi-cylindrical lenses, instead of the vertical grid-shaped parallax barrier, to separate one image on a display screen or panel into a left-eye image and a right-eye image, allowing viewers to enjoy 3D images.
Recently, there is a growing demand for a 3D display device that is switchable between a 2D mode and a 3D mode. This type of display device may selectively display any one of a 2D image and a 3D image depending on an image signal provided from a display screen or panel. To meet this demand, several types of 2D/3D-switchable auto-stereoscopic display devices have been developed.
Referring to FIG. 1, a conventional auto-stereoscopic display device may include a backlight unit 14, a Liquid Crystal Display (LCD) panel 10, and a lenticular means 15, which can switch between a 2D mode and a 3D mode. The LCD panel 10 includes an array of pixels 12 arranged in rows and columns. The LCD panel 10 is scanned by light from the backlight unit 14. Light incident on the LCD panel 10 is changed by the individual pixels 12, depending on appropriate driving voltages applied thereto, to generate desired images.
The lenticular means 15 is disposed on the LCD panel 10. The lenticular means 15 includes a transparent lenticular sheet or lenticular lens sheet 30, on which multiple parallel cylindrical lenses 16 are arranged, a transparent flat-surfaced plate 36 facing the lenticular lens sheet 30, transparent electrodes 34 and 37, which are formed on inner sides of the lenticular lens sheet 30 and the flat-surfaced plate 36, respectively, and an electro-optical medium 38 in the space between the two transparent electrodes 34 and 37. The electro-optical medium 38 may include an appropriate liquid crystal material, i.e., may generally include nematic liquid crystal. The lenticular lens sheet 30 has one flat surface by being molded (or processed) from optically transparent polymer materials, and its screen is formed in a convex-ribbed shape defined by contours of lenses. In this structure, if there is no potential applied between the two electrodes 34 and 37, the lenticular means 15 may run the same as the lenticular lens sheet 30, so it separates one image on the LCD panel 10 into a left-eye image and a right-eye image for a viewer, allowing the viewer to enjoy 3D images. On the contrary, if an appropriate potential is applied between the two electrodes 34 and 37, a refractive index of the electro-optical medium 38 may be substantially identical to a refractive index of the lenticular lens sheet 30 in the viewing direction, removing the lens effects of the lenticular lenses 16. In this case, the lenticular means 15 may act as a permeable plate that merely passes 2D images from the LCD panel 10.